Keyboard lock for typewriting machines



June 6, 1950 A. c. Ho| T 2,510,577

KEYBOARD Locx FOR TYPEWRITING MACHINES Filed June 5. 1947 INVENOR ALBERTHOLT m2 www ATTO R N EY Patented June 6, 1950 KEYBOARD LOCK FORTYPEWRITING MACHINES Albert C. Holt, Ridgewood, N. J., assigner toInternational Business Machines Corporation, New York, N. Y., acorporation of New York Application June 5, 1947, Serial No. 752,720

7 Claims.

This invention relates to typewriting machines, more particularly tothat class of typewriting machine which is operated by motor power.

An object of the present invention is to provide an improved key lockingdevice.

Another object is to provide a key locking device which is actuated bythe end-play of a suitable shaft or other rotary member with which themachine is ordinarily provided.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 shows the key locking device as applied to a conventional form ofelectrically operated typewriting machine and shows the keys in lockedcondition.

Fig. 2 is a View similar to Fig. l but showing the keyboard unlocked.

The invention is shown in the drawings as applied to the well knownElectromatic power operated typewriter but it will be understood thatthis disclosure is purely for convenience in making clear the nature ofthe invention and that the invention may be applied to other poweroperated typewriters or other oflice machines.

The numeral ID designates one of the usual character keys of thekeyboard, which key is suitably pivotally mounted at II on a cross rodsupported by the main framework and at its front end is guided in a slotformed in the usual key guide comb I2. The key locking bar I3 is in theform of a vane pivotally mounted at I4 in the main framework andnormally extends vertically (Fig. 1) so as to lock all of the keysagainst depression. Ordinarily this key locking bar I3 is mechanicallyconnected to the lever of the switch which turns on current to the usualdriving motor and is arranged so that when the switch is on the keylocking bar I3 is in the position shown in Fig. 1.

In the present case provision is made for operating the key locking barI3 so as to render it ineffective when the machine is started, whichmeans is arranged to become automatically effective to lock the keyboardas soon as anything happens which would cause the machine to stop. Forexample, it sometimes happens that the usual extension cord connectingthe machine to the current outlet becomes disengaged from the outletwithout the operators knowledge, with the result that keys are oftenoperated before it is Vdiscovered that the motor is not running. This isvery apt to happen in a noisy room. As soon as current is placed on themachine then all of the function devices controlled by the operated keysbecome effective at once and are partially operated. Usually asufficient number of character keys are depressed to cause a pluralityof type bars to operate at once with the result that they jam in thetype basket and stall the motor.

According to the present invention advantage is taken of end-play whichmay be incidental to some rotating part in the machine or some partwhich may be caused to have end-play for the purpose of operating thekey locking bar I3. A machine of this type is usually provided with someform of worm reduction gear because of the fact that small appliancemotors are necessarily of the high speed type in order to obtain thenecessary amount of power with a small compact motor.

In the drawings, I5 generally designates the usual worm reduction gearfound in the well known Electromatic typewriter. This reduction gearconsists of a suitable housing within which is journaled a worm Wheel IBdriving the usual power roller I1 for the type bars and otherinstrumentalities and mechanisms of the machine. This power rollerrotates in the direction of the arrow all of the time the machine is inuse. Meshing with the worm wheel I6 is a worm I8 formed in a spindle I9turning in the fixed bearing 20 and in a threaded end plug 2|. At itsleft hand end the spindle I9 is provided with a cross pin 22 extendinginto slots formed in the end of the motor shaft 23.

The spindle I9 is slidable in the bearing 29 and the end plug 2| andwhen the machine is at rest, occupies the position shown in Fig. 1 withrthe pin 22 at the closed end of the slot in the shaft 23. The spindleI9 is held in this position by a spring 24 interposed between a collaror enlargement I9a on the spindle I9 and the bearing 29. 'Ihe right handend of the spindle I9 is rounded and engages a lug formed in an L-shapedlever 25 pivoted at 26 to a Xed part of the machine. This lever 25 isurged in a clockwise direction into engagement with the end of spindleI9 by a torsion spring 21. One arm of the lever 25 is slotted to embracea pin 28a formed in a lever 28 pivoted at 28h to a xed part of themachine. The lever 28 has a pin and slot connection 2919 to an arm 29secured to the key locking bar I3. The spindle I9 also has anenlargement I9b designed to limit rightward movement of the spindle I9by engaging the plug 2l.

The worm housing is usually filled with a relatively stiif, heavy greasewhich naturally makes the worm Wheel I6 turn a little stiiily in thehousing and this stiifness is augmented by the friction of the shaft forthe worm wheel and various other parts which are connected to ornormally driven by the worm wheel. Furthermore, the power roller i? isquite long and fairly heavy and it also has considerable inertia. Thespindle I9, on the other hand, is relatively small and the worm I8 isabove the normal level of the grease or oil in the worm housing and, dueto the smaller shaft size, tends to turn comparatively freely.

When the operator closes the switch which energizes the motor, the motorshaft 23 and the spindle iS turn in the direction of the spiral arrow inFig. 1. Due to the stiffness of the grease, the friction of the bearingsand the inertia of the power roller, the worm i9 initially travels tothe right to the position of Fig. 2 by a screwing action beforeproducing any movement of the power roller Il or the worm wheel I6. Thismovement `of the spindle I9 causes the lever 25 to be rockedcounterclockwise, moving the key locking bar .i3 in the same direction,through the lever 23, to

the position of Fig. 2. As soon as the stop por- .r

tion I 9b strikes the plug ZI the worm I8 will turn the power roller andthe parts will be maintained in this position as long as the motorremains in operation.

If the switch is opened or if the connecting cord to the motor is pulledout while the machine is in operation the motor will immediately slowdown and stop and allow the spring 2d to push the spindle back to theposition of Fig. 1, thereby locking the keys against operation. ylhus,if the power should fail while the machine is running, the keyboard willbe very quickly locked.

While there have been shown and described and pointed out thefundamental novel features of the invention, as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit of the invention. It isthe intention,therefore, to be limited only as indicated by the scope of the followingclaims.

What is claimed is:

l. In combination with the keys of a typeriting machine, a key lockingmember, a power driving train including a member having an initialend-play when the driving train is s and means actuated by sad end-playfor dis abling the locking member.

2. In combination with the function keys of a typewriting machine, meansto lock said keys against operation, a power roller for actuating thefunction devices controlled by said keys, a driving motor, gear meansconnecting said moto-r to said power roller and including a. memberhaving va lost motion incidental to starting said motor, and meansactuated by the lost motion of said member for disabling said lockingmeans.

3. In combination with the function keys of a typewriting machine, meansto lock said keys against operation,l power mechanism for actuating thefunction devices controlled by said keys, a driving motor, drivingconnections between said motor and said power mechanism including amember having an end-play movement when said motor starts to drive saidpower mechanism, and means enabling said end-play movement to disablesaid locking means.

4. In combination with the function keys of a typewriting machine, meansto lock said keys against operation, power mechanism for actuating thefunction devices controlled by said keys, a driving motor, drivingconnections between said motor and power mechanism including 3, worm'wheel connected to said power mechanism and a worm connected to saidvmotor and having a limited axial motion, when said motor is started, inconsequence of a threading movement between the worm and worm wheel; andmean actuated by said worm in its axial movement for releasing thelocking means.

5. lin combination with recording means and selectable devices forcontrolling the recording means, means for locking the selectabledevices against operation, power mechanism for actuating the recordingmeans under control of said selectable devices; motive power means forthe power mechanism, including an element having a take-up motion whenthe motive power means is started, and means enabling said take-upmotion to disable said locking means.

6. in combination with the keyboard of a keyboard controlled machine,means to prevent operation of the keyboard, power operating meanscontrolled by said keyboard, a power driving train for said power means,including a member having an initial idle take-up motion when thedriving train is started, and means responsive to said idle motion fordisabling said preventing means.

7. In combination with the keyboard of a keyboard controlled machine,means to prevent operation of said keyboard, a main power actuator forthe function devices controlled by said keyboard, a motive power unit,and driving connections between said main power actuator and said powerunit, including a member having a preliminary idle motion for disablingthe pre venting means before the actuator is started in operation "bythe power unit.

ALBERT C. HOLT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,940,155 Thompson Dec. 19, 19332,287,475 Helmond June 23, 1942

